java中concat()方法的使用说明

public class Test {
  public static void main(String[] args){  
  String s = "厉害了，";
  String str1 = "我的";
  String str2 = "国！";
  
  s = s.concat(str1);//将字符串str1接到字符串s后面
  s = s.concat(str2);//将字符串str1接到字符串s后面
  
  System.out.println(s);
  }  
}

public static void main(String[] args) {
 String str1 = "yveshe";
 String str2 = "hello";

 /**
  * concat
  */
 System.gc();
 long startTime1 = System.currentTimeMillis();
 for (int i = 0; i < 10000; i++) {
  str1 = str1.concat(str2);
 }
 long endTime1 = System.currentTimeMillis();
 System.out.println("concat：" + (endTime1 - startTime1));

 /**
  * +
  */
 str1 = "yveshe";
 System.gc();
 long startTime2 = System.currentTimeMillis();
 for (int i = 0; i < 10000; i++) {
  str1 = str1 + str2;
 }
 long endTime2 = System.currentTimeMillis();
 System.out.println("+: " + (endTime2 - startTime2));
}